Roderick Usher wrote a letter to the narrator asking him to see if because he was sick. Once the narrator gets to the house, he notices the houses condition, which is "sickly" and then the narrator notices that Usher himself is pale and sickly.
Climax
Roderick tells the narrator that his twin sister Madeline is dying. She passes and Roderick decides to keep her body in a wall. The narrator notices Madeline's cheeks are still rosy and her chest is still flushed. Ushers condition worsened after her death.
Falling Action
After Madeline was placed in the wall in the wall, the narrator heard strange noises. One night, Usher comes into the narrators room during a storm and the narrator read him a book to calm him down.
Resolution
As the narrator is reading, the sounds he's describing begins to echo in the house. Once the narrator reaches the climax, there's a scream and Roderick falls over and starts rocking back and forth. Soon the door flies open and Madeline appears.
Madeline then falls on top on Roderick and dies. Then Roderick also dies due to fear. The narrator flees.
Once the narrator is far away from the house, he turns around to see the house falling in on itself.